1. Field of the Invention
This present invention relates to a video encoding system and method featuring an adaptive one-pass variable bit rate controller with scene change detection.
2. Description of the Prior Art
In recent years, technology on digital compression has been widely applied to compress files of various video formats to save the transmission bandwidth or storage capacity. Generally speaking, the most widely adopted techniques are the MPEG (Motion Picture Experts Group) standards established by the ISO (International organization for standardization), such as MPEG-1, MPEG-2, MPEG-4, etc.
It is well known that a MPEG compliant video encoder compresses an input video sequence to achieve a target bit rate defined by the bandwidth of a user-desired video channel before it is transmitted or saved in a storage device. However, when the compressed video sequence associated with a scene, encoded with a constant bit rate, is decoded, the quality of the decoded video sequence will significantly depend on the complexity of the scene.
In practical application, the video sequence is compressed with a variable bit rate. The so-called variable bit rate technique improves the quality of video encoding by adaptively allocating bit rates according to the complexity of the scene. Basically, the rate control for video encoding can be categorized into two fields: one is multi-pass variable bit rate; and the other is single pass variable bit rate. The multi-pass variable bit rate technology utilizes the complexity information of the scene through preceding passes to achieve the target bit rate constraint. The single pass variable bit rate technology adjusts encoding rate dynamically through encoding process. The multi-pass variable bit rate algorithm for video encoding usually provides better picture quality; however, it also requires a larger amount of memory and more expensive computational cost. Therefore, such kind of variable bit rate technique is not suitable for real-time applications. On the other hand, the single pass variable bit rate algorithm cannot guarantee a consistent quality for the entire sequence, especially those sequences with abrupt scene changes.
The main objective of this invention is to provide a video encoding system and method using an adaptive one-pass variable bit rate controller with scene change detection to resolve the problems mentioned above.